text: # -*- mode: python; coding: utf-8 -*-
  # Copyright (C) 2016 Laboratoire de Recherche et Développement de
  # l'Epita
  #
  # This file is part of Spot, a model checking library.
  #
  # Spot is free software; you can redistribute it and/or modify it
  # under the terms of the GNU General Public License as published by
  # the Free Software Foundation; either version 3 of the License, or
  # (at your option) any later version.
  #
  # Spot is distributed in the hope that it will be useful, but WITHOUT
  # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  # License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  import spot
  
  lcc = spot.language_containment_checker()
  
  formulas = ['GFa', 'FGa', '(GFa) U b',
              '(a U b) U c', 'a U (b U c)',
              '(a W b) W c', 'a W (b W c)',
              '(a R b) R c', 'a R (b R c)',
              '(a M b) M c', 'a M (b M c)',
              '(a R b) U c', 'a U (b R c)',
              '(a M b) W c', 'a W (b M c)',
              '(a U b) R c', 'a R (b U c)',
              '(a W b) M c', 'a M (b W c)',
              ]
  
  # The rewriting assume the atomic proposition will not change
  # once we reache the non-alive part.
  cst = spot.formula('G(X!alive => ((a <=> Xa) && (b <=> Xb) && (c <=> Xc)))')
  
  for f in formulas:
      f1 = spot.formula(f)
      f2 = f1.unabbreviate()
      f3 = spot.formula_And([spot.from_ltlf(f1), cst])
      f4 = spot.formula_And([spot.from_ltlf(f2), cst])
      print("{}\t=>\t{}".format(f1, f3))
      print("{}\t=>\t{}".format(f2, f4))
      assert lcc.equal(f3, f4)
      print()
  